Emily Hampshire opens up about her character's onscreen affair with the late "Glee" star, captured before his untimely death in July.

TORONTO -- Late Glee star Cory Monteith's darker, more adult performance in All the Wrong Reasons is set to surprise his fans. Director Gia Milani's debut feature will receive its world premiere Sunday night at the Toronto International Film Festival.

That radical departure from Monteith's former role as Finn Hudson on the Fox series includes his first on-camera love scene, where it was three's a crowd recalls co-star Emily Hampshire.

"When you're doing a romantic scene, it's kind of awkward. And it's all very choreographed. So we were just laughing because this was Gia's first movie. She'd never directed two actors in a love scene," Hampshire told The Hollywood Reporter on Sunday.

"I remember her [Milani] being shy about telling us to -- 'Can you put a hand here, and is that OK?' So we were taking care of her more," she added.

Here was Monteith, as ever the genuine and generous actor that his castmembers on Glee also remember in recent tributes, before he tragically died in Vancouver on July 13 due to an accidental overdose of heroin and alcohol.

"On movies like this that you're doing for no money, where we're all sharing a trailer, the biggest star coming into the movie sets the tone. And he really set a tone of just wanting to be there for the work, and with no ego involved," Hampshire insisted.

Monteith would fly back and forth between Los Angeles, where he was doing press for Glee, and the Halifax set for All the Wrong Reasons, and never complain, she added.

The actor's early stint as a Walmart greeter before becoming a Hollywood star drew Monteith to the role of big-box store manager dealing with a wife (Karine Vanasse) with intimacy issues due to post-traumatic stress disorder.

That troubled home life leads Monteith's character into an affair with a party-girl cashier (Hampshire) who dreams of marrying the store manager to end her own personal woes.

"Both of our inner turmoil brings us together," Hampshire recalls of her own and Monteith's onscreen characters.

She adds the Sunday night festival launch for All the Wrong Reasons will be bittersweet without Monteith on hand.

"He would definitely be proud of the movie and would want it here. But being here without him is sad," Hampshire said.

Toronto is also debuting another movie that Monteith starred in, McCanick, which has its world premiere on Monday night.